Method of transmission through single wire

ABSTRACT

The invention provides a method of transmission through single wire. The method includes receiving a single-wire signal through a single wire; identifying a start code of the single-wire signal; after identifying the start code, counting a rising edge, a falling edge, or both rising edge and falling edge of the single-wire signal in at least one bit transmission period having a fixed length, to generate a count code; and decoding the count code to generate transmitted information.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to a method of transmission through singlewire, especially a method using simple signal transmission protocol totransmit complicated information through single wire.

2. Description of Related Art

For communication between two circuits such as between a powermanagement device and another device, popular communication interfacessuch as I2C, SPI, and SMBUS require at least two wires, one for data andanother for clock signal. It would be beneficial if data and clocksignal can be transmitted by one single wire, because the circuit pinnumber can be reduced, and it is not necessary to synchronize the clocksignals between the receiving circuit and the transmitting circuit. U.S.Pat. Nos. 7,127,631 and 7,080,266 disclose a single wire transmissionmethod as shown in FIG. 1, wherein when the receiving circuit detects arising edge of the signal EN/SET transmitted through the signal wire, itis enabled to receive data as shown by the signal ENABLE, and thereceiving circuit generates a clock signal (CLOCK) according to thesignal EN/SET. A counter of the receiving circuit begins to count therising edges (1˜n) of the signal EN/SET. When the receiving circuitdetects a falling edge of the signal EN/SET, it begins to count atime-out period. If no rising edge is detected within the time-outperiod, the signal ENABLE is stopped; the counter is reset, and theclock signal CLOCK is stopped.

The aforementioned prior art patents count the rising edges from lowlevel to high level, and the count represents the transmittedinformation. Thus, to transmit a number n, n rising edges have to betransmitted. The larger the transmitted number is, the more rising edgesare needed, and the transmission period (bit length) is longer.Apparently, this method is inconvenient for transmitting a very largenumber, and because the length of the transmission period is not fixed,it causes some problems in certain applications.

In view of foregoing, the present invention provides a method oftransmission through single wire, which is capable of transmittingcomplicated information through single wire by simple protocol.

SUMMARY OF THE INVENTION

In one perspective, the present invention provides a method oftransmission through single wire, which includes: receiving asingle-wire signal through a single wire, wherein the single-wire signalincludes a plurality of rising edges and a plurality of falling edges;identifying a start code of the single-wire signal; after identifyingthe start code, counting a number of rising edge(s), falling edge(s), orboth rising edge(s) and falling edge(s) of the single-wire signal in atleast one bit transmission period having a fixed length, to generate acount code; and decoding the count code to generate transmittedinformation.

In the foregoing method, plural bit transmission periods can betransmitted, and each bit transmission period represents a bit.

In another perspective, the present invention provides a method oftransmission through single wire, which transmits a single-wire signalto a receiving circuit through a single wire. The single-wire signalincludes: a start code; a plurality of bit transmission periods, eachbit transmission period representing a bit and including at least onelevel switching to represent a count code; and a transmission end code.

According to one preferable embodiment of the present invention, thestart code can be a rising edge or falling edge of the single-wiresignal.

In a preferable embodiment of the present invention, the count code isdecoded to obtain a digital 1 or 0 according to whether the count codeis even or odd, respectively, or is decoded to obtain a digital 0 or 1according to whether the count code is even or odd, respectively.

In a preferable embodiment of the present invention, a numberrepresented by a notation higher than binary notation can be transmittedin a bit transmission period.

In a preferable embodiment of the present invention, the single-wiresignal further includes a transmission end code; the transmission endcode includes a high level or a low level which lasts for apredetermined time period, wherein the predetermined time period startsfrom an end of the last bit transmission period, or from a rising edgeof the plurality of rising edges or a falling edge of the plurality offalling edges.

In a preferable embodiment of the present invention, no clockinformation is required in the single-wire transmission.

In a preferable embodiment of the present invention, the transmittedinformation includes one of a command, an address, and read/write data,or a combination thereof.

The objectives, technical details, features, and effects of the presentinvention will be better understood with regard to the detaileddescription of the embodiments below, with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a prior art method of sequential transmission throughsingle wire.

FIG. 2 shows two embodiments of the single-wire signals according to thepresent invention.

FIG. 3 shows rising edges and falling edges of the single-wire signalsaccording to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The drawings as referred to throughout the description of the presentinvention are for illustration only, but not drawn according to actualscale.

The present invention provides a method of transmission through singlewire, which includes: receiving a single-wire signal through a singlewire, wherein the single-wire signal includes plural rising edges andplural of falling edges; identifying a start code of the single-wiresignal; after identifying the start code, counting a number of risingedge(s), falling edge(s), or both rising edge(s) and falling edge (s) ofthe single-wire signal in at least one bit transmission period having afixed length, to generate a count code; and decoding the count code togenerate transmitted information.

FIG. 2 shows two preferable embodiments of a single-wire signal receivedby a receiving circuit. The two preferable embodiments are differentfrom each other in their background levels: one with a background ofhigh level, and the other with a background of low level. Thesingle-wire signal includes a start code SA which indicates a start ofthe signal transmission. The start code SA for example can be a risingedge or a falling edge of the single-wire signal; of course, other morecomplicated forms can be options to define the start code. In theembodiment shown at the upper part of FIG. 2, the start code SA isrepresented by a falling edge. In contrast, in the embodiment shown atthe lower part of FIG. 2, the start code SA is represented by a risingedge. After indentifying the start code SA, a receiving circuit (notshown in figure) counts the number of level switching(s) (which may berising edge(s), or falling edge(s), or both rising edge (s) and fallingedge (s) of the single-wire signal) in a first bit transmission periodT1 having a fixed length, to generate a count code. In both of the twoembodiments shown in FIG. 2, the receiving circuit counts the fallingedge(s), which are only examples and the receiving circuit certainly cancount rising edges or both rising edge(s) and falling edge(s). Theobtained count can be encoded and decoded in various ways, which will bedescribed in more detail later. The single-wire signal can include morethan one bit; as an example, the single-wire signals shown in FIG. 2include two bits which are respectively transmitted in bit transmissionperiods T1 and T2 (both having the same fixed length). The single-wiresignal preferably includes a transmission end code to indicate an end ofthe transmission. In one embodiment, the transmission end code usestime-out mechanism, i.e., if there is no level switching in a period oftime, it indicates the end of the transmission. Referring to the upperpart of FIG. 2, in this example, the transmission end code is expressedby a time-out period TE in which there is no level switching, whereinthe time-out period TE starts from the end of a bit transmission period(T2 in the shown example). Or, referring to the lower part of FIG. 2,the transmission end code is expressed by a time-out period TE′ in whichthere is no level switching, wherein the time-out period TE′ starts froma level switching (a rising or falling edge, in this example a fallingedge). The signal can stay at either high or low level during thetime-out period.

In the bit transmission period, the obtained count can be regarded as acode (count code) which can be encoded and decoded in various ways. Onesuch way is to decode the count code into binary information; forexample, the count code can be decoded as a binary 0 when the count offalling edges of the single-wire signal is odd, and the count code canbe decoded as a binary 1 when the count of falling edges is even. Or, itcan certainly be arranged otherwise such that the count code is decodedas a binary 1 when the count of falling edges is odd, and the count codeis decoded as a binary 0 when the count of falling edges is even. In thetwo embodiments shown in FIG. 2, in the first bit transmission periodT1, the count of falling edges of the single-wire signal is 3 (oddnumber), so the count code can be decoded as a binary 0. In the secondbit transmission period T2, the count of falling edges of thesingle-wire signal is 2 (even number), so the count code can be decodedas a binary 1. Thus, the single-wire signal can include binaryinformation of 0's and 1's. It should be noted that the single-wiresignal is shown to include only two bit transmission periods in FIG. 2,but this is only an example; the single-wire signal can certainlyinclude only one bit transmission period or more bit transmissionperiods, which should all belong to the scope of the present invention.

The count code can be encoded and decoded in other ways. For example,the count of falling edges of the single-wire signal in the first bittransmission period T1 is 3, and this number (3) can be defined as aspecific command, address, or read/write data. Or, the number (3) timescan be used to represent an integer, such as 2 (the number 1 torepresent the integer 0). Every bit transmission period can represent abit, and the bit is not limited to a bit expressed by binary notation,that is, the bit can be a number expressed by a notation higher thanbinary notation. In this regard, different from the prior art U.S. Pat.Nos. 7,127,631 and 7,080,266, the bit transmission period of the presentinvention has a fixed length, and a large number can be encoded withplural count codes (combination of plural bit transmission periods).Combination of two or more bit transmission periods can be used todefine desired information such as commands, addresses, read/write data,or combinations thereof.

The count code can be obtained by counting the rising edge(s) or bothrising and falling edge(s) of the single-wire signal instead of thefalling edge(s). Referring to FIG. 3, in the fixed time period T3, thecount code can be obtained by counting the rising edge(s), fallingedge(s), or both edges of the single-wire signal no matter thebackground level is high level or low level. The above-mentionedprinciples can be applied here with respect to encoding/decoding,definition of binary 0/1, count code, and the meaning of combination ofcount codes, etc.

As described in the above, the present invention can transmitcomplicated information by a single wire without clock information(i.e., no other wire is required for transmitting the clockinformation). In comparison with the prior art, the present inventionrequires shorter transmission time for transmitting a large number, andthe transmission period has a fixed length. If the number of thetransmitted bits is fixed, then the total transmission time is alsofixed; this is advantageous in many applications.

In one embodiment of the present invention, for communication betweendevices, the transmitted information can be arranged to include acommand, an address, read/write data, or a combination thereof. Forexample, it can be so arranged that in each transmission, 1st˜mth bitsrepresent command, (m+1)th˜(m+1+n)th bits represent address, and(m+1+n+1)th˜(m+1+n+1+p)th bits represent read/write data, etc.

The present invention has been described in considerable detail withreference to certain preferred embodiments thereof. It should beunderstood that the description is for illustrative purpose, not forlimiting the scope of the present invention. An embodiment or a claim ofthe present invention does not need to achieve all the objectives oradvantages of the present invention. The title and abstract are providedfor assisting searches but not for limiting the scope of the presentinvention. Those skilled in this art can readily conceive variations andmodifications within the spirit of the present invention. For example,the start code can instead be defined as two sequential rising edges, orthe transmission end code can instead be defined as a combination of onerising edge and one falling edge, etc. In view of the foregoing, thespirit of the present invention should cover all such and othermodifications and variations, which should be interpreted to fall withinthe scope of the following claims and their equivalents.

What is claimed is:
 1. A method of transmission through single wire,comprising: receiving a single-wire signal through a single wire,wherein the single-wire signal includes a plurality of rising edges anda plurality of falling edges; identifying a start code of thesingle-wire signal; after identifying the start code, counting a numberof rising edge(s), falling edge(s), or both rising edge(s) and fallingedge(s) of the single-wire signal in at least one bit transmissionperiod having a fixed length, to generate a count code, wherein each bittransmission period represents one bit of the single-wire signal; anddecoding the count code to generate transmitted information, wherein thecount code is decoded to obtain a digital 1 or 0 according to whetherthe count code is even or odd, respectively, or is decoded to obtain adigital 0 or 1 according to whether the count code is even or odd,respectively.
 2. The method of claim 1, wherein the start code is arising edge of the plurality of rising edges or a falling edge of theplurality of falling edges of the single-wire signal.
 3. The method ofclaim 1, wherein plural bit transmission periods are transmitted.
 4. Themethod of claim 1, wherein a number represented by a notation higherthan binary notation is transmitted in a bit transmission period.
 5. Themethod of claim 1, wherein the single-wire signal further includes atransmission end code, the transmission end code including a high levelor a low level which lasts for a time-out period, wherein the time-outperiod starts from an end of the bit transmission period, or from arising edge of the plurality of rising edges or a falling edge of theplurality of falling edges.
 6. The method of claim 1, wherein thetransmitted information comprises a command, an address, read/writedata, or a combination thereof.
 7. A method of transmission throughsingle wire, comprising: transmitting a single-wire signal to areceiving circuit through a single wire, the single-wire signalincluding: a start code; a plurality of bit transmission periods havinga same fixed length, each bit transmission period representing a bit andincluding at least one level switching to represent a count code; and atransmission end code, wherein the count code is decoded to obtain adigital 1 or 0 according to whether the count code is even or odd,respectively, or is decoded to obtain a digital 0 or 1 according towhether the count code is even or odd, respectively.
 8. The method ofclaim 7, wherein the start code is a rising edge or falling edge of thesingle-wire signal.
 9. The method of claim 7, wherein a numberrepresented by a notation higher than binary notation is transmitted ina bit transmission period.
 10. The method of claim 7, wherein thetransmission end code includes a high level or a low level which lastsfor a time-out period, wherein the time-out period starts from an end ofa last one of the plurality of bit transmission periods, or from arising edge or a falling edge.
 11. The method of claim 7, wherein thetransmitted information includes one of a command, an address,read/write data, or a combination thereof.